Merge ~kissiel/plainbox-provider-snappy:set-volume-in-alsa-test into plainbox-provider-snappy:master

[Maciej Kisielewski]

alsa_test: set playback and capture volumes when starting the test

This should improve the fails on some device that default to muted or low gain capture.

If any of the mixer shenanigans fails the test plows on, so this should be "backwards compatible".

[Sylvain Pineau (sylvain-pineau)]

LGTM

review: Approve

[Chris Wayne (cwayne)]

Doesnt fix the issue on Dawson-j

review: Needs Fixing

[Maciej Kisielewski (kissiel)]

> Doesnt fix the issue on Dawson-j

This patch is a general improvement, that did not fix the problem on that particular device, while it fixes a problem where the mixer state would prevent the testing.

Also from what I can tell it doesn't break anything, so I would like to land it.

diff --git a/src/alsa_test.cpp b/src/alsa_test.cpp
index e536f82..b5f4bd6 100644
--- a/src/alsa_test.cpp
+++ b/src/alsa_test.cpp
@@ -266,6 +266,46 @@ template<>
 snd_pcm_format_t Alsa::Pcm<uint8_t>::get_alsa_format() {
     return SND_PCM_FORMAT_U8;
 }
+
+struct Mixer {
+    Mixer(string card_name, string mixer_name) {
+        int res;
+        res = snd_mixer_open(&mixer_handle, 0);
+        if (res < 0) throw AlsaError("Failed to open an empty Mixer");
+        res = snd_mixer_attach(mixer_handle, card_name.c_str());
+        if (res < 0) throw AlsaError("Failed to attach HCTL to a Mixer");
+        res = snd_mixer_selem_register(mixer_handle, NULL, NULL);
+        if (res < 0) throw AlsaError("Failed to register a Mixer");
+        res = snd_mixer_load(mixer_handle);
+        if (res < 0) throw AlsaError("Failed to load a Mixer");
+        snd_mixer_selem_id_alloca(&sid);
+        snd_mixer_selem_id_set_index(sid, 0);
+        snd_mixer_selem_id_set_name(sid, mixer_name.c_str());
+        elem = snd_mixer_find_selem(mixer_handle, sid);
+        if (!elem) throw AlsaError(mixer_name + " mixer not found.");
+    }
+    ~Mixer() {
+        snd_mixer_close(mixer_handle);
+    }
+    void set_all_playback_volume(float volume) {
+        long min, max;
+        snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
+        int new_vol = int(float(max) * volume);
+        snd_mixer_selem_set_playback_switch_all(elem, 1);
+        snd_mixer_selem_set_playback_volume_all(elem, new_vol);
+    }
+    void set_all_capture_volume(float volume) {
+        long min, max;
+        snd_mixer_selem_get_capture_volume_range(elem, &min, &max);
+        int new_vol = int(float(max) * volume);
+        snd_mixer_selem_set_capture_switch_all(elem, 1);
+        snd_mixer_selem_set_capture_volume_all(elem, new_vol);
+    }
+private:
+    snd_mixer_t *mixer_handle;
+    snd_mixer_selem_id_t *sid;
+    snd_mixer_elem_t* elem;
+};
 }; //namespace Alsa
 
 template<class storage_type>
@@ -359,6 +399,17 @@ int main(int argc, char *argv[]) {
     if (std::find(args.begin(), args.end(), std::string("-v")) != args.end()) {
         logger.set_level(Logger::Level::info);
     }
+    try {
+        auto playback_mixer = Alsa::Mixer("default", "Master");
+        auto capture_mixer = Alsa::Mixer("default", "Capture");
+        playback_mixer.set_all_playback_volume(0.75f);
+        capture_mixer.set_all_capture_volume(0.75f);
+    } catch(Alsa::AlsaError err) {
+        logger.normal() << "Failed to change volume: " << err.what() << std::endl;
+        // not being able to change the volume is not critical to the test
+        // and for some devices "Master" and "Caputre" mixers may not exist
+        // so let's just print warning if that's the case
+    }
     auto format = std::string("int16_48000");
     auto format_it = std::find(args.begin(), args.end(), std::string("--format"));
     if (format_it != args.end()) { // not doing && because of sequence points